Hallo Daryl:

the good reputation of the 6,5x55 in Sweden comes from the use of long and heavy buillets with a weigt of 156gr.
In the swedish law it is just allowed to shoot moose with a minimum-calibre of 6.5mm and a minimum-buillettweigt of 10g (=154gr.).
The buillet must have a power of 2000Joule (=1476ft.lb.) at a distance of 100m (=110yds.).
Or an buillet with 9g (=139gr.) minimum-weigt, and a power of 2700Joule (=1992ft.lb.) on 100m.
The penetration in the game-body with the thin and long buillets in the 6.5 and 7mm-calibres is mutch better, than the thick and short 150gr. buillets in cal. .30.
And just with this long and thin buillets you become good results at bigger games. A shot in a angle-position to the heavy game made a shot with a smallbore-calibre and a light buillet very difficult.
If the 7x57 will mostley used on moose or the heavy deer-species like elk or crown-deer it is the best to use the heavy 160-175gr. buillets.
The 7x57 was never made for heavy games, for this species were the 8x57, the 9x57 or the 9,3x62 the better choises if you like german cartriges.
(By americ. cartriges .30-06, 8mm-06 or .35Whelen)

regards
Manolito